Ignition distributor rotor

United States Patent 3887780

To reduce the potential magnitude necessary to break down the spark gap between the spark gap electrode of an ignition distributor rotor and each of the output electrodes in the distributor cap, an auxiliary electrode of an electrically conductive material is placed in electrical contact with the spark gap electrode and so located as to aid the ionization of the spark gap between the spark gap electrode and each of the output terminals.

05/398564

06/03/1975

09/18/1973

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General Motors Corporation (Detroit, MI)

200/19.33

313/149

F02P7/02; F02P7/00; (IPC1-7): H01H3/00

200/19DR,3R,31CA,181,19DC 313

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3632965	ELECTRICALLY HEATED DISTRIBUTOR CAP	January 1974	Guth
3197580	Ventilated terminal ignition distributor cap	July 1965	Zelulka
3035107	Distributor for internal combustion engine	May 1962	Matveeff et al.
2972024	Distributor	February 1961	Behrbaum
2799792	Ignition systems for internal combustion engines	July 1957	Flint
2684451	Spark intensifier for spark plugs	July 1954	Castongay
2678365	Ignition distributor	May 1954	Bales
2555488	Distributor rotor	June 1951	Hetzler
1981021	Ignition distributor rotor	November 1934	Arthur
1265918	N/A	May 1918	Kennington

Myhre, Charles J.

Devinsky, Paul

Stahr, Richard G.

This application is a continuation-in-part of application Ser. No. 377,646, filed July 9, 1973.

What is claimed is

1. An ignition distributor rotor of the type which is rotated by a driving shaft within a distributor cap having a center input terminal and a plurality of output terminals circumferentially arranged about the input terminal comprising: a body member of an electrically nonconductive material adapted to be rotated by said driving shaft, a spark gap electrode of an electrically conductive material supported by and having a tip portion extending beyond an edge of said body member which is passed in spark gap relationship with successive ones of said output terminals as said body member is rotated by said shaft, and an auxiliary electrode of an electrically conductive material in electrical contact with said spark gap electrode and positioned in register with said spark gap electrode along a common radius and extending beyond the edge of said body member in the direction of said tip portion of said spark gap electrode.

2. An ignition distributor rotor of the type which is rotated by a driving shaft within a distributor cap having a center input terminal and a plurality of output terminals circumferentially arranged about the input terminal comprising: a body member of an electrically nonconductive material adapted to be rotated by said driving shaft, a spark gap electrode of an electrically conductive material supported by and having a tip portion extending beyond an edge of said body member which is passed in spark gap relationship with successive ones of said output terminals as said body member is rotated by said shaft, a contact member of an electrically conductive material in electrical contact with said spark gap electrode and arranged to be electrically connected to said center input terminal of said distributor cap, and an auxiliary electrode of an electrically conductive material in electrical contact with said spark gap electrode positioned in register with said spark gap electrode along a common radius and extending beyond the edge of said body member in the direction of said tip portion of said spark gap electrode.

3. An ignition distributor rotor of the type which is rotated by a driving shaft within a distributor cap having a center input terminal and a plurality of output terminals circumferentially arranged about the input terminal comprising: a body member of an electrically nonconductive material adapted to be rotated by said driving shaft, a spark gap electrode of an electrically conductive material supported by and having a tip portion extending beyond an edge of said body member which is passed in spark gap relationship with successive ones of said output terminals as said body member is rotated by said shaft, and an auxiliary electrode of an electrically conductive material in electrical contact with said spark gap electrode positioned in register with said spark gap electrode along a common radius and extending at a selected angle from said spark gap electrode in the direction of said tip portion thereof.

4. An ignition distributor rotor of the type which is rotated by a driving shaft within a distributor cap having a center input terminal and a plurality of output terminals circumferentially arranged about the input terminal comprising: a body member of an electrically nonconductive material adapted to be rotated by said driving shaft, a spark gap electrode of an electrically conductive material supported by and having a tip portion extending beyond an edge of said body member which is passed in spark gap relationship with successive ones of said output terminals as said body member is rotated by said shaft, a contact member of an electrically conductive material in electrical contact with said spark gap electrode and arranged to be electrically connected to said center input terminal of said distributor cap, and an auxiliary electrode of an electrically conductive material in electrical contact with said spark cap electrode positioned in register with said spark gap electrode along a common radius and extending at a selected angle from said spark gap electrode in the direction of said tip portion thereof.

5. An ignition distributor rotor of the type which is rotated by a driving shaft within a distributor cap having a center input terminal and a plurality of output terminals circumferentially arranged about the input terminal comprising: a body member of an electrically nonconductive material adapted to be rotated by said driving shaft, a spark gap electrode of an electrically conductive material supported by and having a tip portion extending beyond an edge of said body member which is passed in spark gap relationship with successive ones of said output terminals as said body member is rotated by said shaft, and an elongated contact member of an electrically conductive material in electrical contact with said spark gap electrode along a common radius with one end thereof arranged to be electrically connected to said center input terminal of said distributor cap and the other end thereof extending at a selected angle from said spark gap electrode beyond the edge of said body member in the direction of said tip portion of said spark gap electrode.

The subject invention is directed to an ignition distributor rotor and, more specifically, to an ignition distributor rotor having an auxiliary electrode of an electrically conductive material in electrical contact with the spark gap electrode and so located as to aid the ionization of the spark gap between the spark gap electrode and each of the distributor cap output terminals.

It has been found that use of the modern, high dielectric strength electrically nonconductive materials for the body member of distributor rotors substantially increased the magnitude of the voltage required to ionize and, consequently, break down the spark gap between the spark gap electrode supported by the body member and the spark gap between the spark gap electrode and each of the output terminals of the distributor cap. It was also found that excessive radio noise was produced when the potential required to break down each spark gap exceeded approximately 12 kilovolts. Therefore, an ignition distributor rotor having a body member made of a modern, high dielectric strength electrically nonconductive material and including an arrangement of electrodes which reduce the potential magnitude required to break down each ignition distributor spark gap, is desirable.

It is, therefore, an object of this invention to provide an improved ignition distributor rotor.

It is another object of this invention to provide an improved ignition distributor rotor having a body member of a high dielectric strength electrically nonconductive material and an electrode arrangement which reduces the potential required to break down the distributor spark gaps.

In accordance with this invention, an ignition distributor rotor is provided having a body member of electrically nonconductive material which carries a spark gap electrode of an electrically conductive material having a tip portion extending beyond an edge of the body member and an auxiliary electrode of an electrically conductive material in electrical contact with the spark gap electrode and so located as to aid the ionization of the spark gap between the spark gap electrode and each of the distributor cap output terminals.

For a better understanding of the present invention, together with additional objects, advantages and features thereof, reference is made to the following description and accompanying drawing in which:

FIG. 1 is a vertical section view of a portion of an ignition distributor showing the distributor rotor member of this invention mounted therein;

FIG. 2 is a side view of the distributor rotor member of this invention; and

FIG. 3 is a top view of the distributor rotor member of this invention.

In the several FIGURES of the drawing, like elements have been assigned like numerals of reference.

As is well known in the automotive art, the ignition distributor rotor 10, FIG. 1, is rotated by a driving shaft 11, usually gear coupled to the camshaft of the associated internal combustion engine, within a distributor cap 12 having a center input terminal 13, to which is connected one end of the associated ignition coil secondary winding, and a plurality of output terminals 14, 15, 16 and 17 circumferentially arranged about the input terminal 13, to which the spark plugs are connected through respective spark plug leads in a manner well known in the automotive art. Although only four output terminals are shown in the drawing, in which the distributor cap 12 is illustrated in cross-section, it is to be specifically understood that an output terminal is provided for each of the engine spark plugs and that they are circumferentially arranged about the center input terminal in a manner well known in the automotive art.

The ignition distributor rotor of this invention comprises a body member 20 of an electrically nonconductive material adapted to engage and be rotated by driving shaft 11, a spark gap electrode 21 of an electrically conductive material supported by and having a tip portion 21a extending beyond an edge of body member 20 which is passed in spark gap relationship with successive ones of the output terminals of distributor cap 12 as body member 20 is rotated by shaft 11, an auxiliary electrode 25 of an electrically conductive material in electrical contact with spark gap electrode 21 and so located as to aid the ionization of the spark gap between spark gap electrode 21 and each of the output terminals of the distributor cap and a contact member 30 of an electrically conductive material in electrical contact with spark gap electrode 21 and arranged to be electrically connected to center input terminal 13 of distributor cap 12. In a practical application, the electrically nonconductive material of which body member 20 was made was a 40% talc filled polypropylene plastic. Body member 20 may be secured to the centrifugal weight base 26 by screws 27 and 28. As weight base 26 is rotated by shaft 11 in a manner well known in the art, rotor member 20 is rotated therewith. One example of an ignition distributor with which the distributor rotor of this invention may be used is described in U.S. Pat. No. 2,872,537, Hartzell et al., assigned to the same assignee as this application. It is to be specifically understood, however, that any other arrangement through which body member 20 is adapted to engage and be rotated by driving shaft 11 may be employed without departing from the spirit of this invention.

In the preferred embodiment illustrated in the drawing, contact member 30 is shown to be an elongated contact member of an electrically conductive material in intimate electrical contact with spark gap electrode 21 with one end thereof arranged to be electrically connected to center input terminal 13 of distributor cap 12 through carbon ball 31, and the other end thereof extending at an angle from spark gap electrode 21 beyond the same edge of body member 20 to form auxiliary electrode 25. That is, contact member 30 and auxiliary electrode 25 are provided by a single, elongated strip of an electrically conductive material. With this arrangement, the ignition spark potential produced by the secondary winding of the associated ignition coil may be delivered to successive ones of the distributor cap output terminals as rotor body member 20 is rotated by shaft 11 in timed relationship with the associated internal combustion engine, in a manner well known in the automotive art, through center input terminal 13, carbon ball 31, contact member 30, spark gap electrode 21 and the spark gap between spark gap electrode 21 and each of the distributor cap output terminals. In a practical application, rotor body member 20 included an integral boss 35 of the same material having a channel 36 of a width which accommodated spark gap electrode 21 and auxiliary electrode 25 and of a depth greater than the total thickness of these two electrodes when arranged as shown in FIG. 1. Small nibs 37, 38, 39 and 40 projecting inwardly from and normal to the side walls of boss 35 which define channel 36 were arranged to engage the spark gap and auxiliary electrodes and were ultrasonically deformed to maintain these electrodes securely in position on body member 20. It is to be specifically understood that alternate methods of maintaining these electrodes securely in position on body member 20 may be employed without departing from the spirit of the invention.

It is to be specifically understood that it is not necessary that auxiliary electrode 25 be integral with the contact member 30 but may be a separate electrode of an electrically conductive material in intimate electrical contact with spark gap electrode 21 having a portion thereof which extends at an angle from spark gap electrode 21 in a direction toward the distributor cap output terminals.

The angle at which auxiliary electrode 25 extends from spark gap electrode 21 does not appear to be particularly critical, it being only necessary that it be in electrical contact with spark gap electrode 21 and positioned as to aid the ionization of the spark gap between spark gap electrode 21 and each of the distributor cap 12 output terminals.

It is believed that when a high dielectric strength electrically nonconductive material is employed as body member 20, the body member holds an electrostatic charge because of its extremely high resistance characteristics. It is believed that the larger positive ions are stored on the rotor in the vicinity of the spark gap electrode and are not discharged or bled away by the high dielectric strength material used as the body portion. Consequently, as the rotor voltage builds up for the next spark, the positive ions which approach the rotor tip are repelled by the positive ions stored on the high dielectric material of body member 20 which causes the sparking potential to increase to a higher level to fire the gap. These stored positive ions are apparently dispersed by the auxiliary electrode, a condition which reduces the required potential to ionize and break down the arc gap.

In a practical application of the rotor of this invention, the required breakdown potential was below 10 kilovolts.

It was also found that conductive paint or pencil marks on the surface of body member 20 in the vicinity of spark gap electrode 21 reduced the magnitude of the potential required to ionize and break down the arc gaps so long as there was an electrical connection between these paint or pencil marks and spark gap electrode 21.

While a preferred embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various modifications and substitutions may be made without departing from the spirit of the invention which is to be limited only within the scope of the appended claims.